Two Nigerians executed by firing squad on Nusakambangan prison island for drug smuggling were buried Friday at Nirbaya, about six kilometers from the prison on the same island.

Nirbaya is a former prison used during the Dutch colonial era where political prisoners linked to the now-defunct Indonesian Communist Party and those facing subversion charges were executed in 1985 and 1987 respectively.

Samuel Iwachekwu Okoye and Hansen Anthoni Nwaolisa were executed around midnight on Thursday on the prison island, situated off the coast of Central Java.

Both Okoye and Nwaolisa were caught smuggling some seven kilograms of heroin into the country through Soekarno Hatta airport in 2001.

Their requests for clemency from President Susilo Bambang Yudhoyono were rejected in 2004.

The executions were conducted by two team of firing squads from the Central Java Police's Mobile Brigade in cooperation with representatives of the prosecutors' office, said Bambang Winahyo, head of the Central Java office of the Legal Affairs and Human Rights Ministry, in Semarang on Friday.

"The executions ran smoothly....we deployed a platoon of security officers to help safeguard the process of the executions," said Cilacap Police chief Adj. Sr. Comr. Teguh Pristiwanto.

Such a deployment was needed as on Monday dozens of convicts on death row at the prison were angered after the two convicts were not given a second chance to appeal for amnesty.

Bambang Triwahono also expressed disappointment over the executions. "We haven't had a response for our second appeal for amnesty, but why were the executions carried out?" he said.

One day before the executions, the two convicts through their lawyers formally demanded the Attorney General postpone the executions.

The Cilacap Police chief said the two were declared dead about 10 minutes after they were shot in the heart once by the firing squads.

Despite the executions, Bambang said he did not want to make any new legal moves as the convicts' families had been informed of the decision.

The Nusakambangan prison has housed 43 convicts on death row for various cases. The dates of executions are decided on by the Attorney General.